What are the next steps after an MRI of the knee following a fall?

Next Steps After MRI of the Knee Following a Fall

After an MRI of the knee following a fall, management should be guided by the specific findings on imaging, with MRI without IV contrast being the most appropriate next imaging study after radiographs do not show fracture, to evaluate for suspected occult fractures or internal derangement. 1

Algorithmic Approach Based on MRI Findings

For Soft Tissue Injuries

• If meniscal tears are identified (present in up to 47% of knee MRIs, especially in those with osteoarthritis), determine if surgical or conservative management is needed based on:
  • Size and location of tear 2
  • Presence of mechanical symptoms (locking, catching) 3
  • Patient's age and activity level 2

For Ligamentous Injuries

• Medial collateral ligament (MCL) injuries:

  • Grade I-II injuries: Conservative management with bracing and physical therapy 3
  • Grade III injuries: May require surgical repair if unstable 1

• Anterior cruciate ligament (ACL) injuries:

  • Complete tears typically require surgical reconstruction, especially in younger, active patients 3
  • Partial tears may be managed conservatively in select cases 1, 3

• Posterior cruciate ligament (PCL) injuries:

  • Most can be managed conservatively with rehabilitation 3
  • Surgical intervention for multi-ligament injuries or persistent instability 1

• Lateral collateral ligament (LCL) injuries:

  • Often require surgical management due to instability 3

For Bone Injuries

• Tibial plateau fractures:

  • If identified on MRI after negative radiographs, further evaluation with CT may be appropriate 1
  • MRI or CT without IV contrast is equally appropriate for evaluating additional bone or soft-tissue injury after radiographic diagnosis of tibial plateau fracture 1

• Bone marrow edema/contusions:

  • Usually managed conservatively with weight-bearing restrictions and pain control 4
  • Monitor for development of osteonecrosis in severe cases 1

For Vascular Concerns

• If knee dislocation is suspected or confirmed:
  • Evaluate for vascular injury with CTA lower extremity with IV contrast 1
  • Popliteal artery injuries require prompt surgical intervention to preserve limb function 1
  • MRA may be performed simultaneously with MRI for evaluation of internal derangement and vascular injuries 1

Special Considerations

For Older Adults (>50 years)

• Falls in older adults with knee pain double the risk of multiple falls 5
• Address modifiable risk factors identified in the MRI evaluation:
  • Strengthen quadriceps muscles to improve knee extension torque 5
  • Improve balance through targeted exercises 5
  • Address psychological concerns about falling 5

For Post-Arthroplasty Falls

• Urgent evaluation is needed if the fall occurred within 8 weeks of surgery 6
• Emergency surgical irrigation and debridement is required if there is:
  • Copious bleeding from the surgical wound 6
  • Rupture of the parapatellar surgical wound 6
  • Disruption of the quadriceps repair 6

Common Pitfalls to Avoid

• Overreliance on MRI findings: In patients over 50 years with osteoarthritis, MRI findings may not always alter management (only 23% of cases with documented pre-MRI plans had management changes based on MRI) 2

• Failure to obtain radiographs first: The majority (62.2%) of patients getting knee MRIs did not have recent radiographs, which should be the first-line imaging 2

• Missing vascular injuries: In cases of significant trauma or knee dislocation, vascular assessment is critical as injuries to the popliteal artery require prompt surgical intervention 1

• Inadequate follow-up: Patients with knee injuries after falls need appropriate rehabilitation to prevent recurrent falls, especially older adults with knee pain who have double the risk of multiple falls 5